People with intellectual disability are twice as likely to experience sexual abuse, unintended pregnancies, and sexually transmitted diseases as people in the general population. Despite this, very little is known about how to deliver Relationships and Sex Education effectively for this vulnerable population, how to measure the impact of its delivery in schools and what stakeholders perceive as important outcomes of this education.

To address these urgent issues, this study aims to develop a stakeholder consensus-based Core Outcome Set of Relationships and Sex Education for use in research and educational settings with students with intellectual disability.

The study will use a two-stage mixed-methods design. The first stage will involve a systematic review of Relationships and Sex Education outcomes reported in the literature, followed by qualitative exploration with parents, teachers, school staff, policy makers and researchers to investigate their perspectives of meaningful outcomes of this education. Students with intellectual disability will be enabled to take part to express their views on outcomes of importance to them. The second stage will use findings from stage 1 in a two round online Delphi study with parents, teachers, school staff, policy makers and researchers to develop consensus on proposed outcomes for the evaluation of Relationships and Sex Education with this population.

The results will provide a standardised set of outcomes of Relationships and Sex Education be used in research and educational settings with students with intellectual disability.

The development of a Core Outcome Set of Relationships and Sex Education will provide a significant first step to assist the implementation, delivery, evaluation, and sustainability of Relationships and Sex Education for students with intellectual disability. Key audiences will be teachers, researchers, and policy- and decision- makers

The study is registered prospectively in the Core Outcome Measures in Effectiveness Trials (COMET) database (registration number: CRD42021243176). The systematic review is registered in the International Prospective Register of Systematic Reviews (PROSPERO) (registration number: 1787).